no75 2008
Mopeds can easily be overlooked

  Although the number of people killed in traffic accidents while riding a motorcycle decreased considerably in 2007 compared to that of 2000 - by about 40,000 (20%) to 147,938, a great number of motorcycle riders, as many as about 150,000, are still injured in traffic accidents. From among motorcycle categories classified by mode of traveling according to engine displacement, this issue of ITARDA Information features crossing collisions involving mopeds, the most fatal type of accident, and analyzes the human factors in the riders and drivers of the involved cars. Particular focus is placed on how a relatively small moped is seen by a car driver before an accident occurs.

Section 1 Characteristics of traffic accidents involving motorcycles
Section 2 Crossing collisions involving mopeds (analysis of statistical study database)
2-1  Accidents by primary/secondary party*3 and casualties by age group
2-2  Forms of crossing collisions involving mopeds
Section 3 In-depth analysis of factors in crossing collisions (analysis of in-depth study database)
3-1  Crossing collisions covered in the analysis
3-2  Analysis of human factors in crossing collisions involving mopeds
3-2-1  Classification of recognition/judgment errors
3-2-2  Analysis of recognition errors against a crossing vehicle
3-2-3  Analysis of judgment errors against crossing vehicles
Section 4 Examples of accidents
Case 1: Motor vehicle driver overlooking a moped running near the left edge of the road and concealed by trees
Case 2: Both drivers overlooking each other's vehicle (1)
Case 3: Both drivers overlooking each other's vehicle (2)


  Traffic accidents are caused by both parties committing errors with multiple factors within the process of recognition, judgment and operation. Given that most accidents were triggered by errors made by Parties A, accidents could be prevented if Parties A did not commit errors. Similarly, considering the fact that inappropriate errors made by Parties B, such as the assumption that "that driver also recognizes my presence, so I can go first", have provoked some accidents even though they had recognized the presence of the other vehicle, accidents could be avoided if Parties B try defensive driving to prepare for a sudden movement of the other vehicle.

The present analysis revealed that mopeds involved in crossing collisions are frequently overlooked because of their characteristic mode of travel (running near the left edge of the road) and small size (easily concealed by another vehicle, trees, billboards, roadside objects, etc.). In addition, mopeds (motorcycles) under mixed traffic conditions are sometimes involved in accidents because other drivers mistakenly evaluate their position and speed due to their small size compared to relatively big motor vehicles.

The following are tips necessary to avoid crossing collisions based on the above results:

- Mopeds are inconspicuous and easily overlooked.
Be sure to attract other drivers' attention while driving, namely by not being concealed.
In particular, be sure to keep a sufficient distance from the vehicle in front in order not to be concealed by that vehicle.

- Position and speed of mopeds are easily misjudged.
Be sure to decelerate when you recognize the presence of a vehicle at an intersection.
Because of the relatively small size of a moped compared to a motor vehicle, keep in mind that its speed and position are easily misjudged by the other driver.

- Moped riders often make incorrect judgments based on mistaken assumptions.
Be sure not to make optimistic assumptions.
Even if you have recognized the presence of the other vehicle, it does not necessarily mean that the other driver also recognizes your presence.

- Accidents triggered by motor vehicles are often due to a lack of rechecking.
When entering an intersection, be sure to check the right side twice.

Institute for Traffic Accident Research and Data Analysis (ITARDA)